1. Technical Field
The present invention relates to a sensor element, a force detection device, a robot, an electronic component transport device, an electronic component inspection device, and a component processing device.
2. Related Art
In recent years, an industrial robot has been progressively introduced into production facilities such as factories in order to improve production efficiency. This industrial robot includes an arm which can be driven in one or more axial directions, a hand attached to a distal end of the arm, and an end effector of a component inspection device, a component transport device, and a component processing device. The industrial robot can carry out various tasks such as component manufacturing work including component assembly work, component processing work, and component inspection work, and component transport work.
In this industrial robot, a force detection device is disposed between the arm and the end effector. The force detection device includes a piezoelectric element (charge output element) which outputs a charge in response to an applied external force, and a conversion circuit (converter) which converts the charge output from the piezoelectric element into a voltage, and can detect the external force applied to the piezoelectric element. The industrial robot uses this force detection device so as to detect the external force generated during the component manufacturing work or the component transport work. Based on a detection result, the industrial robot controls the arm and the end effector. As a result, the industrial robot can accurately carry out the component manufacturing work or the component transport work.
As this force detection device, a quartz crystal-type piezoelectric sensor using quartz crystal as the piezoelectric element is widely used (for example, refer to JP-A-10-68665). The quartz crystal-type piezoelectric sensor disclosed in JP-A-10-68665 is widely used in the industrial robot since the quartz crystal-type piezoelectric sensor has excellent characteristics such as a wide dynamic range, high stiffness, high natural frequency, and strong resistance against a load.
However, in this quartz crystal-type piezoelectric element, the charge output from the quartz crystal is weak. Accordingly, it is not possible to ignore influence of output drift which is caused by temperature changes. In particular, even when the external force is not applied, there is a possibility that stress is generated in the quartz crystal by thermal expansion caused by the temperature changes. This stress may cause a possibility that the charge is detected in the quartz crystal-type piezoelectric element even when the external force is not applied.
As described above, according to the quartz crystal-type piezoelectric element in the related art, there is a possibility of a problem such as poor detection accuracy caused by the temperature changes.